#returnToTopButton {
    --bottom: 3vh;
    --bottom2: -100px;
    min-width: 50px;
    min-height: 50px;
    position: fixed;
    right: 3vw;
    bottom: var(--bottom2);
    opacity: 0;
    display: flex;
    background-color: #1e293b;
    border: 2px solid var(--borderColor);
    border-radius: 5px;
    z-index: 10000;
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

#returnToTopButton>img {
    width: 70%;
    height: 20%;
    transform: rotate(180deg);
}

.returnToTopButton-appear{
    animation: appear 0.5s cubic-bezier(0.38, -0.22, 0.61, 1.24) forwards
}

.returnToTopButton-disappear{
    animation: disappear 0.5s ease-in-out forwards
}

/* 返回顶部按钮-出现动画 */
@keyframes appear {
    0% {
        bottom: var(--bottom2);
        /*opacity: 0;*/
    }
    100% {
        bottom: var(--bottom);
        /*opacity: 0.5;*/
    }
}

/* 返回顶部按钮-消失动画 */
@keyframes disappear {
    0%   {
        bottom: var(--bottom);
        /*opacity: 0.5;*/
    }
    100% {
        bottom: var(--bottom2);
        /*opacity: 0;*/
    }
}